Conductive adhesives containing conductive fillers dispersed in binder resins are used to mount electronic components on substrates. When pressure bonding is performed with a conductive adhesive interposed between a terminal of an electronic component and a wire arranged on a substrate, the conductive filler particles interposed between the terminal and the wire come into contact with each other and extend to form a conductive path. Examples of this type of conductive adhesive include those in which an insulating filler in addition to a conductive filler are dispersed; and those in which a binder resin therefor contains a cross-linker used to promote the crosslinking between base resin molecules to increase the molecular weight, as described in Patent Documents 1 to 3. Patent Document 1 describes that a base resin preferably has a weight-average molecular weight of 10,000 or more and less than 1,000,000 in order to enhance the mixing properties with another material to be mixed. Patent Document 2 describes that poly(oxypropylenediamine) having a molecular weight of 2,000 or more and less than 5,000 or Jeffamine (registered trademark) having a molecular weight of 2,000 or more and less than 4,000 is used as a cross-linker for an epoxy resin. Patent Document 3 exemplifies an average particle size of 4 μm of a conductive filler and an average particle size of 3 μm of an insulating filler.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011-179006
Patent Document 2: Japanese Unexamined Patent Application Publication No. 11-343397
Patent Document 3: Japanese Patent No. 4816827